FlatFix Calculator (Flat Fee + % Fee)
Figure out how much to charge so you still receive your exact target amount after payment processor fees.
What is a FlatFix calculator?
A flatfix calculator helps you solve one of the most common pricing problems: payment fees are usually a mix of a flat fee and a percentage fee. If you set your price without accounting for both, you can end up earning less than you intended.
This tool works backward. Instead of asking “How much will I get from this price?”, it asks “What price should I charge to receive my target net amount?” That makes it useful for freelancers, digital creators, ecommerce sellers, coaches, consultants, and anyone collecting online payments.
Why this matters for income planning
Even small fees create a meaningful difference over time. A flat fee hits low-priced items especially hard, while percentage fees scale with larger invoices. If you sell frequently, poor pricing can silently reduce your annual income by hundreds or thousands of dollars.
- Protect your profit margins from underpricing
- Quote clients accurately the first time
- Avoid “fee shock” after payment arrives
- Build cleaner financial forecasts
How the FlatFix formula works
Core equation
If your processor charges a percentage plus a flat amount, the amount you must charge before tax is:
Required charge = (Target net + Flat fee + Other fixed costs) / (1 − Percentage fee)
Example: If you want to keep $100, and fees are 2.9% + $0.30, then:
Required charge = (100 + 0.30) / (1 − 0.029) = $103.30 (rounded)
If you apply sales tax or VAT on top, that amount is added after the required charge is calculated.
When to use this calculator
- Sending project invoices where your net amount must be exact
- Pricing digital products, memberships, and templates
- Running a small online store with gateway fees
- Comparing fee structures across payment providers
- Deciding whether to absorb fees or pass them through
Practical pricing tips
1) Use net-based pricing targets
Start with how much you need to keep, not with what looks “nice” on the storefront. Your net is what pays your bills and funds growth.
2) Revisit fees quarterly
Payment processors and platform policies can change. Re-check assumptions every few months so your margins remain healthy.
3) Include hidden fixed costs
If each sale has fixed handling expenses, include them in the calculator. Many businesses forget this and wonder why cash flow feels tighter than expected.
4) Decide a clean rounding rule
Round to a consistent pricing style (e.g., $29.00, $49.00, or $49.99). Keep your catalog coherent and easy to explain.
Common mistakes to avoid
- Ignoring the flat fee on low-ticket products
- Using percentage as a whole number in formulas (2.9 vs 0.029)
- Assuming tax is your revenue
- Forgetting to account for refunds/chargebacks in planning
- Setting one universal markup for all product price levels
Frequently asked questions
Does this replace accounting software?
No. It is a fast decision tool for pricing and quoting. You should still record final numbers in your bookkeeping system.
Can I use it for marketplaces?
Yes, as long as the fee model is “percentage + fixed fee.” If your platform has tiered or category-based fees, run separate scenarios for each category.
What if my fee percentage is very high?
The math becomes unstable as fees approach 100%. In real business conditions, percentages that high usually mean the pricing model itself needs rethinking.
Bottom line
A good flatfix calculator helps you stop guessing and start pricing with precision. Use it before publishing prices, sending proposals, or launching new offers. Small improvements in pricing discipline compound into stronger margins and more predictable income.